A device according to the invention may be embodied as a fingerprint scanner capable of obtaining a fingerprint image of one or more fingers using ultrasound measurement techniques. Such a device may move an ultrasound transducer in a substantially planar arc, substantially parallel to a measurement surface, while linearly advancing the arc so as to produce a raster type scan image.
Multiple ultrasound transducers may be positioned on a rotatable disk. In this manner, information about the fingerprint or fingerprints (as the case may be) may be rapidly collected as a raster image representative of the fingerprint(s) of the finger or fingers. The invention may have the added advantage that, because of conservation of momentum, a smaller motor may be used and the flywheel effects of the rotating disk may allow for a more stable image than with prior art systems.
Ultrasound imaging has the ability to capture a fingerprint image in conditions considered by most fingerprint imaging systems to be severe and adverse. Ultrasound systems perform better than other types of systems when contaminants, such as oil, dirt, ink and grime, are present. Ultrasound systems also are able to capture images from a small portion of the population normally considered to be difficult to fingerprint because they have very finely detailed, worn or abraded fingerprint friction surface ridges.